yvan-ext/assets/ext-7.4.0.42/classic/theme-material/sass/var/panel/Tool.scss

$tool-close-glyph: dynamic('close'); 
$tool-collapse-left-glyph: dynamic('keyboard_arrow_left'); 
$tool-collapse-right-glyph: dynamic('keyboard_arrow_right');  
$tool-collapse-top-glyph: dynamic('keyboard_arrow_up'); 
$tool-collapse-bottom-glyph: dynamic('keyboard_arrow_down');  
$tool-expand-left-glyph: dynamic('keyboard_arrow_left'); 
$tool-expand-right-glyph: dynamic('keyboard_arrow_right');  
$tool-expand-top-glyph: dynamic('keyboard_arrow_up'); 
$tool-expand-bottom-glyph: dynamic('keyboard_arrow_down');  
$tool-maximize-glyph: dynamic('fullscreen');  
$tool-minimize-glyph: dynamic('fullscreen_exit');  
$tool-gear-glyph: dynamic('settings');